Gas electrodes, for example oxygen electrodes, are well known in the art and are useful in many processes including chlor-alkali processes and processes for the production of hydrogen peroxide. Oxygen electrodes are generally porous. In such electrodes, reactions occur at the point(s) where there is a three-phase contact between a gas, an electrolyte solution and a solid electrical conductor. To maximize the efficiency of the electrode, the amount of the three-phase contact area should be maximized. If the electrode is filled with the electrolyte, the rate of mass transfer of gas to the electrical conductor is too slow to be significant and is therefore not useful. Conversely, if the electrode is filled with gas, the absence of the electrolyte solution allows only insignificant amounts of reactions to occur.
Packed bed electrolytic cells of the type described in U.S. Pat. Nos. 3,969,201 and 4,118,305 are commonly used. A porous separator separates the packed bed electrode from the adjoining electrode and is supported by the packed bed electrode. The pores of the separator are sufficiently large to allow free flow of electrolyte into the openings of the packed bed electrode. Electrochemical reactions occur within the electrode at a gas-electrolyte-electrode interface. The liquid products and unreacted electrolyte flow by gravity to the bottom of the packed bed electrode. Mass transfer is a problem in such cells because the electrode is almost flooded with electrolyte. Reactions are slow and recycle of the product is necessary.